Histological, electron microscopic, and immunocytochemical studies of herpetic stromal keratitis in animal models are carried out to determine the mechanism of immunopathogenesis. Spleen cell preparations from immune and non-immune normal (nu/ion) heterozygote mice are transferred to athymic (nu/nu) mice to study the effect of specific cell populations on the development of stromal keratitis in the athymic mice. Immunization of rabbits by injection of a heat-killed vaccine into the limbus of the eye, and subsequent protection against herpetic stromal keratitis is also studied.